The present invention relates to a format and formatting process for data storage media, and more particularly to a method for using offset information on a data storage medium e.g., to provide unique identification information.
The Internet and many other sources now provide a vast array of streaming and fixed media content for listening and/or viewing. However, currently there is no practical way of capturing or recording the audio and/or video portion of the streaming or fixed media in a copy-protected manner so that a user can listen to or view the presentation at a later time, but also so that the user cannot freely copy and distribute the recorded material. This problem has existed in connection with other media rendering and recording devices e.g., VCRs for television content, or tape recorders for audio signals, but with at least one key difference. Since digital media content can be recorded with virtually no signal loss, this poses a xe2x80x9criskxe2x80x9d for copyright owners that their works will be freely shared (pirated) without compensation. With VCRs and tape recorders, the device(s) and transmission media invite noise or corruption of data into the recording process. With streaming or fixed digital media, there is no reason why virtually lossless conversions and re-transmissions cannot be effected, at least to the limits of human ear capabilities, and there is no reason why unadulterated digital data cannot be stored and freely distributed. Thus, it would be desirable to prevent unfettered re-distribution of digital data because there is little difference between what copyright owners can provide for a fee and what one""s friends, randomly located servers or even anonymous client devices, e.g., in the case of peer to peer networks like NAPSTER(copyright) and GNUTELLA(copyright), can provide for free. Thus, with respect to streaming content, there is currently no practical way for the recorded data to be stored xe2x80x9csecurelyxe2x80x9d on a user""s computer and also locked to that computer or storage medium with certain rights applied, otherwise known as Digital Rights Management (DRM).
DRM has thus received a lot of attention as a result of the ease with which digital data can be re-distributed ad infinitum without corruption. DRM systems have thus attempted to implement methods for encrypting music and applying certain digital rights to that piece of media with the express intent that you can not copy it, re-distribute it, or play the file without the right from the copyright holder to do so. For example, one system has a unique electronic serial number assigned to each disk. This serial number can be and is used as a key to secure and unlock digital music with its associated rights. For example, a particular digital sound file can be secured using the serial number on a portable disk for a portable disk player, so that the song can only be played when that disk is inserted into the system thus preventing re-distribution of the song. For example, commonly assigned copending U.S. patent application Ser. No. 09/891,441 and related copending patent applications by the assignee of the present application describe the utilization of a medium""s serial number in connection with a DRM licensing scheme in order to tie content to a particular medium, and the concomitant mass production of such media.
Storage media, and in particular re-writeable storage media, are at times shipped from a storage media manufacturer/distributor with pre-determined data already stored thereon. This includes not only unalterable structures on the media such as servo marks and sync fields, but also, for example, data packaged on the media that may be tied to the serial number of the disk. Such pre-packaged data may include one or more software programs, one or more data structures, one or more data files, and/or the like. Likewise, the re-writeable storage media may be a magnetic or optical in nature, and may be a tape, a disk, or the like. Moreover, the storage media may be read-only, write-only, read-write, or the like, as appropriate.
Once the storage media is shipped with the already-stored data, though, such storage media is quite obviously out of the hands of the manufacturer/distributor, who is then powerless to prevent anyone from making changes to the stored data on the storage media. Thus, at the front end of the storage medium manufacturing and formatting, it would be beneficial to provide robust and unalterable unique information for possible use in connection with a storage medium""s serial number, and for further possible use in connection with a DRM licensing technique. It would be further desirable to leverage existing manufacturing and formatting infrastructure to create such robust and unalterable unique information. Thus, there is a need in the art for the provision of unalterable information on a medium that may nonetheless be flexibly altered upon creation in order to contain unique information relative to other media formatted according to the same process.
In this regard, media that store data along tracks have required methods for keeping a tracking head aligned with the center of a track, so that errors in reading and writing data do not occur. One traditional method is to provide marks, such as servo fields, on the storage medium in order to guide an actuator head by way of feedback from the marks. Thus, various techniques have been developed for writing/positioning servo marks on a recording medium for such purpose, and in various patterns. It would thus be desirable to leverage existing infrastructure for writing servo fields at formatting time for the purpose of providing unique information on a storage medium. It would be further desirable to create unique servo fields with graycodes that contain unique information, different from information contained in a servo field. It would be still further desirable to provide a variable offset in connection with the unique graycodes, whereby the information represented by the variable offset is combinable with the information embodied by the unique graycodes to form a flexible, unalterable, and unique number that may be retrieved by the electronics of a data storage device and/or form a basis for the serial number of the data storage medium.
The present invention provides a technique for providing offset information on a storage medium by providing at least one unalterable mark on the storage medium during a manufacturing formatting process. The unalterable mark(s) are variably offset from a fixed position. The amount of offset represents a first source of unique information. The unalterable mark(s) themselves comprise a second source of information. Both sources of information are combinable and may be utilized in connection with the generation of a unique serial number for the storage medium. Such unique information may also be incorporated into a digital rights management system.
Other features of the present invention are described below.